Display device including an oxide semiconductor which overlaps an opening

ABSTRACT

According to one embodiment, a display device includes a gate line extending in a first direction, first and second source lines crossing the gate line and arranged in the first direction, a first light-shielding layer having first and second openings, and an oxide semiconductor layer crossing the gate line, and in the display device, the first opening and the second opening are arranged in a second direction crossing the first direction between the first source line and the second source line, the gate line is located between the first opening and the second opening, and the oxide semiconductor layer has a first overlapping portion overlapping the first opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/874,199, filed Jan. 18, 2018, which is based upon and claims thebenefit of priority from Japanese Patent Application No. 2017-008620,filed Jan. 20, 2017, the entire contents of all of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

In transmissive liquid crystal display devices, to prevent deteriorationof switching elements and leak current, light-shielding layers servingas shields against light from backlights are provided in some cases. Inliquid crystal display devices used in smartphones and tablet computers,in association with an increase in resolution, there is demand forswitching elements which have a smaller size and can pass a largeramount of current. As the method for passing a large amount of currentto the switching element, it is known that the gate electrode of theswitching element and the light-shielding layer are electricallyconnected to each other and the light-shielding layer is used as a backgate electrode, for example.

However, in the above-described structure, parasitic capacitance betweenwires which constitute a pixel increases, and this may cause degradationin display quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the structure of a display device of thepresent embodiment.

FIG. 2 is a diagram showing the basic structure and the equivalentcircuit of a display panel shown in FIG. 1.

FIG. 3 is a plan view of the structure of a pixel PX.

FIG. 4 is a plan view of the structure of a second substrate.

FIG. 5 is a sectional view of part of the display panel taken along lineA-B shown in FIG. 3.

FIG. 6 is a sectional view of part of the display panel taken along lineC-D shown in FIG. 3.

FIG. 7 is a plan view of another structural example of a firstsubstrate.

FIG. 8 is a sectional view of part of the first substrate taken alongline E-F shown in FIG. 7.

FIG. 9 is a plan view of another structural example of the firstsubstrate.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device includes aninsulating substrate, a gate line extending in a first direction on theinsulating substrate, a first source line and a second source linecrossing the gate line on the insulating substrate and arranged in thefirst direction, a first light-shielding layer overlapping the gateline, the first source line and the second source line and having afirst opening and a second opening, and an oxide semiconductor layercrossing the gate line between the first source line and the secondsource line and connected to the second source line, and in the displaydevice, the first opening and the second opening are arranged in asecond direction crossing the first direction between the first sourceline and the second source line, the gate line is located between thefirst opening and the second opening, and the oxide semiconductor layerhas a first overlapping portion overlapping the first opening.

According to another embodiment, a display device includes an insulatingsubstrate, a gate line extending in a first direction on the insulatingsubstrate, a first source line and a second source line crossing thegate line on the insulating substrate and arranged in the firstdirection, an oxide semiconductor layer crossing the gate line betweenthe first source line and the second source line, and a first pixelelectrode and a second pixel electrode arranged in a second directioncrossing the first direction between the first source line and thesecond source line, and in the display device, the gate line is locatedbetween the first pixel electrode and the second pixel electrode, andthe oxide semiconductor layer includes a first end electricallyconnected to the second pixel electrode, a second end electricallyconnected to the second source line, and a second overlapping portionlocated between the first end and the second end and overlapping thefirst pixel electrode.

Embodiments will be described hereinafter with reference to theaccompanying drawings. Incidentally, the disclosure is merely anexample, and proper changes within the spirit of the invention, whichare easily conceivable by a skilled person, are included in the scope ofthe invention as a matter of course. In addition, in some cases, inorder to make the description clearer, the widths, thicknesses, shapes,etc., of the respective parts are schematically illustrated in thedrawings, compared to the actual modes. However, the schematicillustration is merely an example, and adds no restrictions to theinterpretation of the invention. Besides, in the specification anddrawings, the structural elements having functions, which are identicalor similar to the functions of the structural elements described inconnection with preceding drawings, are denoted by like referencenumerals, and an overlapping detailed description is omitted unlessotherwise necessary.

FIG. 1 shows the structure of a display device DSP of the presentembodiment. A first direction X and a second direction Y shown in thedrawing cross each other. For example, the first direction X and thesecond direction Y orthogonally cross each other, but the firstdirection X and the second direction Y may cross each other at an angleother than an angle of 90 degrees.

In the present embodiment, a liquid crystal display device is explainedas an example of the display device. The main structure disclosed in thepresent embodiment is also applicable to a self-luminous display devicehaving an organic electroluminescent display element, etc., anelectronic paper-type display device having an electrophoretic element,etc., a display device adopting a micro-electromechanical system (MEMS),an electrochromic display device, etc.

The display device DSP includes a display panel PNL, a driver IC chip 1which drives the display panel PNL, etc. The display panel PNL is aliquid crystal display panel, for example, and includes a firstsubstrate SUB1, a second substrate SUB2, a sealant SE and a liquidcrystal layer (liquid crystal layer LC which will be described later).The second substrate SUB2 is opposed to the first substrate SUB1. Thefirst substrate SUB1 and the second substrate SUB2 are attached to eachother by the sealant SE. The display panel PNL includes a display areaDA which displays an image and a non-display area NDA which has theshape of a frame and surrounds the display area DA. The display area DAis located in a region enclosed with the sealant SE.

The driver IC chip 1 is located in the non-display area NDA. In theexample illustrated, the driver IC chip 1 is provided in a mountingportion MT of the first substrate SUB1 which extends outward beyond thesecond substrate SUB2. For example, a display driver which outputs asignal necessary for image display is incorporated in the driver IC chip1. The display driver here includes at least part of a source driver SD,gate drivers GD1 and GD2 and a common electrode driver circuit CD whichwill be described later. The driver IC chip 1 is not limited to theexample illustrated but may be provided on a flexible printed circuitboard which is separately connected to the display panel PNL.

The display panel PNL of the present embodiment may be any one of atransmissive display panel having a transmissive display function ofdisplaying an image by selectively transmitting light from a backsurface side of the first substrate SUB1, a reflective display panelhaving a reflective display function of displaying an image byselectively reflecting light from a front surface side of the secondsubstrate SUB2, and a transflective display panel having thetransmissive display function and the reflective display function.

Further, although detailed description of the structure of the displaypanel PNL is omitted here, the display panel PNL may have a structureconforming to any one of a display mode using a lateral electric fieldalong an X-Y plane or a main surface of a substrate, a display modeusing a longitudinal electric field along a normal of the X-Y plane, anda display mode using an oblique electric field which is oblique with theX-Y plane. Still further, the display panel PNL may have a structureconforming to a display mode using an arbitrary combination of thelongitudinal electric field, the lateral electric field and the obliqueelectric field.

FIG. 2 shows the basic structure and the equivalent circuit of thedisplay panel PNL shown in FIG. 1. The display panel PNL includes aplurality of pixels PX in the display area DA. The pixels PX arearranged in a matrix. Further, the display panel PNL includes aplurality of gate lines G (G1 to Gn), a plurality of source lines S (S1to Sm), a common electrode CE, etc., in the display area DA. The gatelines G extend in the first direction X and are arranged in the seconddirection Y, respectively. The source lines S extend in the seconddirection Y and are arranged in the first direction X, respectively. Thegate lines G and the source lines S are not necessarily extendedlinearly but may be partially bent. The common electrode CE is arrangedover the pixels PX.

The display panel PNL includes the gate drivers GD1 and GD2 and thesource driver SD in the non-display area NDA. The gate driver GD1 andthe gate driver GD2 face each other across the display area DA in thefirst direction X. The gate lines G are connected to one of the gatedrivers GD1 and GD2. The odd-numbered gate lines G1, G3, . . . areconnected to the gate driver GD1 in the example illustrated. Theeven-numbered gate lines G2, G4, . . . are connected to the gate driverGD2. According to this layout, the width at one edge and the width atthe other edge can be uniformed in the non-display area NDA, and this issuitable for narrowing the frame. The source lines S are connected tothe source driver SD. The common electrode CE is connected to the commonelectrode driver circuit CD. The source driver SD, the gate drivers GD1and GD2 and the common electrode driver CD may be formed on the firstsubstrate SUB1 or may be partially or entirely incorporated in thedriver IC chip 1 shown in FIG. 1, in the non-display area NDA.

Each pixel PX includes a switching element SW, a pixel electrode PE, thecommon electrode CE, a liquid crystal layer LC, etc. The switchingelement SW is formed of a thin-film transistor (TFT), for example, andis electrically connected to the gate line G and the source line S. Thegate line G is connected to the respective switching elements SW of thepixels PX arranged in the first direction X. The source line S isconnected to the respective switching elements SW of the pixels PXarranged in the second direction Y. The pixel electrode PE iselectrically connected to the switching element SW. Each pixel electrodePE is opposed to the common electrode CE, and drives the liquid crystallayer LC by an electric field formed between the pixel electrode PE andthe common electrode CE. Storage capacitance CS is formed between anelectrode having the same potential as that of the common electrode CEand an electrode having the same potential as that of the pixelelectrode PE, for example. The gate line G, the source line S, theswitching element SW, the pixel electrode PE, the common electrode CE,etc., are provided in the first substrate SUB1 shown in FIG. 1.

FIG. 3 is a plan view of the structure of the pixel PX. This is a planview of the first substrate SUB1, which is one of the substrateconstituting the display panel PNL. The example illustrated correspondsto an example adopting a fringe field switching (FFS) mode, which is oneof the display modes using the lateral electric field. The firstsubstrate SUB1 includes the common electrode, for example, but theillustration of the common electrode is omitted here.

The first substrate SUB1 includes the gate lines G2 and G3,light-shielding layers LS2 and LS3, the source lines S1 and S2, pixelelectrodes PE1 and PE2, the switching element SW, etc.

The gate lines G2 and G3 extend in the first direction X and arranged inthe second direction Y at a distance from each other. The gate lines G2and G3 are formed into a strip shape having a substantially constantwidth WG in the second direction Y.

The light-shielding layers LS2 and LS3 extend in the first direction Xand overlap the gate lines G2 and G3, respectively. As a representative,the structure of the light-shielding layer LS2 will be described below.The light-shielding layer LS2 is conductive and is electricallyconnected to the gate line G2. For example, the light-shielding layerLS2 may be electrically connected to the gate line G2 by being connectedto the gate driver GD2 shown in FIG. 2. The light-shielding layer LS2 isformed into a strip shape having a substantially constant width WLS inthe second direction Y and crosses the source lines S1 and S2. The widthWLS is greater than the width WG. Therefore, the gate line G2 entirelyoverlaps the light-shielding layer LS2. In the example illustrated, thegate line G2 is located in a substantially center of the light-shieldinglayer LS2.

The source lines S1 and S2 extend in the second direction Y and arearranged in the first direction X at a distance from each other. In theexample illustrated, the pixel PX corresponds to the region of a cellformed by the gate lines G2 and G3 and the source lines S1 and S2 andhas the shape of a rectangle in which the sides of the rectangle in thefirst direction X are shorter than the side of the rectangle in thesecond direction Y. The shape of the pixel PX is not limited to arectangle but may be appropriately changed.

The pixel electrodes PE1 and PE2 are arranged in the second direction Ybetween the source line S1 and the source line S2. The gate line G2 islocated between the pixel electrode PE1 and the pixel electrode PE2. Asa representative, the structure of the pixel electrode PE2 will bedescribed below.

The pixel electrode PE2 includes an electrode portion PA2 and a contactportion PB2. The electrode portion PA2 and the contact portion PB2 areintegrally or continuously formed with each other and are electricallyconnected to each other. The contact portion PB2 is closer to the gateline G2 than the electrode portion PA2. The electrode portion PA2extends from the contact portion PB2 in the second direction Y. In theexample illustrated, the pixel electrode PE2 has two electrode portionsPA2. The two electrode portions PA2 are arranged in the first directionX at a distance from each other and are formed into a strip shape havinga substantially constant width in the first direction X. The shape ofthe pixel electrode PE2 is not limited to the illustrated example butmay be appropriately changed in accordance with the shape of the pixelPX, etc. For example, the pixel electrode PE2 may extend in an obliquedirection crossing the first direction X and the second direction Y, andthe electrode portion PA2 may extend in the oblique direction. Further,the pixel electrode PE2 may have one electrode portion PA2 or three ormore electrode portions PA2.

The switching element SW is formed between the source line S1 and thesource line S2. For example, the switching element SW is a single-gatethin-film transistor which is electrically connected to the source lineS2 and the gate line G2. The switching element SW includes asemiconductor layer SC2, a gate electrode GE, a relay electrode RE, etc.

The semiconductor layer SC2 is substantially L-shaped, and has a firstportion PS21, a second portion PS22, a first end E1 and a second end E2.The first end E1 of the semiconductor layer SC2 is located between thesource line S1 and the source line S2 and between the gate line G2 andthe gate line G3, and is closer to the gate line G2 than the gate lineG3. The first end E1 overlaps the relay electrode RE and the contactportion PB2. The second end E2 of the semiconductor layer SC2 is locatedon the opposite side to the first end E1 across the gate line G2, andoverlaps the source line S2.

The first portion PS21 extends from the first end E1 in the seconddirection Y, and crosses the gate line G2 and the light-shielding layerLS2. The gate electrode GE corresponds to a portion of the gate line G2which crosses the first portion PS21. The first portion PS21 isconnected to the relay electrode RE in a contact hole CH1 overlappingthe first end E1. In the example illustrated, a region opposite to thefirst end E1 of the first portion PS21 is located between two electrodeportions PA1 of the pixel electrode PE1.

The second portion PS22 extends from the second end E2 in the firstdirection X, and is connected to the first portion PS21. The secondportion PS22 is connected to the source line S2 in a contact hole CH2overlapping the second end E2. The second portion PS22 has anoverlapping portion OV1 which overlaps one of the electrode portions PA1as shown by diagonal lines. The overlapping portion OV1 is locatedbetween the first end E1 and the second end E2. The overlapping portionOV1 and the first end E1 are arranged in the second direction Y. Theoverlapping portion OV1 and the second end E2 are arranged in the firstdirection X.

The second portion PS22 is farther from the gate line G2 and thelight-shielding layer LS2 than an end (fourth end) EPA of the electrodeportion PA1 in the second direction Y. In other words, a distance GPSbetween the second portion PS22 and the gate line G2 is greater than adistance GPA between the electrode portion PA1 and the gate line G2.Similarly, a distance LPS between the second portion PS22 and thelight-shielding layer LS2 is greater than a distance LPA between theelectrode portion PA1 and the light-shielding layer LS2. The distancehere is distance in the second direction Y. In the example illustrated,the distance (fourth distance) LPS is less than the distance (fifthdistance) GPS.

The first portion PS21 may extend in a direction crossing the seconddirection Y, and the second portion PS22 may extend in a directioncrossing the first direction X. Further, the first portion PS21 and thesecond portion PS22 may be partially bent.

The relay electrode RE overlaps the contact portion PB2. In the exampleillustrated, the relay electrode RE is located in a substantially centerof the pixel PX in the first direction X. A width WRE of the relayelectrode RE is greater than a width WPB of the contact portion PB2. Therelay electrode RE is connected to the contact portion PB2 in a contacthole CH3 formed in a region overlapping the contact portion PB2.Accordingly, the pixel electrode PE2 is electrically connected to theswitching element SW via the relay electrode RE. In the exampleillustrated, the contact hole CH3 is closer to the gate line G2 than thecontact hole CH1.

In the example illustrated, the first substrate SUB1 includes asemiconductor layer SC3 crossing the gate line G3. The semiconductorlayer SC3 constitutes the switching element together with the gate lineG3. Similarly to the semiconductor layer SC2, a second portion PS32 ofthe semiconductor layer SC3 crosses the electrode portion PA2.

FIG. 4 is a plan view of a structural example of the second substrateSUB2 opposed to the first substrate SUB1 shown in FIG. 3. The secondsubstrate SUB2 includes a light-shielding layer BM, a color filter,etc., but only the light-shielding layer BM is illustrated here.Further, the structural elements provided in the first substrate SUB1are shown by dashed lines.

The light-shielding layer BM is provided in a region opposed to the gatelines G2 and G3, the light-shielding layers LS2 and LS3, the sourcelines S1 and S2 and the relay electrode RE, and the pixels PX arepartitioned by the light-shielding layer BM. The light-shielding layerBM has openings OP1 and OP2. The openings OP1 and OP2 correspond to aregion of the display panel PNL which contributes to display. In theexample illustrated, the openings OP1 and OP2 are located between thesource line S1 and the source line S2 and are arranged in the seconddirection Y.

The gate line G2 and the light-shielding layer LS2 are located betweenthe opening OP1 and the opening OP2. The relay electrode RE is locatedbetween the gate line G2 and the opening OP2. The semiconductor layerSC2 has an overlapping portion OV2 which partially overlaps the openingOP1 as shown by diagonal lines. That is, the overlapping portion OV2does not overlap the light-shielding layer BM. The overlapping portionOV2 is substantially L-shaped and includes part of the first portion PS2l and part of the second portion PS22. The first end E1 is locatedbetween the gate line G2 and the opening OP2 and overlaps thelight-shielding layer BM. The second end E2 overlaps the source line S2and also overlaps the light-shielding layer BM. The second end E2 isfarther from the gate line G2 than an end (third end) of the opening OP1on the gate line G2 side. In other words, the overlapping portion OV2and the first end E1 are arranged in the second direction Y. Theoverlapping portion OV2 and the second end E2 are arranged in the firstdirection X.

In the present embodiment, the source line S1 corresponds to the firstsource line, the source line S2 corresponds to the second source line,and the gate line G2 corresponds to the gate line. The pixel electrodePE1 corresponds to the first pixel electrode, and the pixel electrodePE2 corresponds to the second pixel electrode. The light-shielding layerBM corresponds to the first light-shielding layer, and thelight-shielding layer LS2 corresponds to the second light-shieldinglayer or the light-shielding layer. The opening OP1 corresponds to thefirst opening, and the opening OP2 corresponds to the second opening.The overlapping portion OV2 corresponds to the first overlappingportion, and the overlapping portion OV1 corresponds to the secondoverlapping portion.

FIG. 5 is a sectional view of part of the display panel PNL taken alongline A-B shown in FIG. 3. In FIG. 5, a direction from the firstsubstrate SUB1 to the second substrate SUB2 is defined as a thirddirection Z. Further, the third direction Z is referred to as up orabove, and the opposite direction to the third direction Z is referredto as down or below.

The first substrate SUB1 includes a first insulating substrate 10, afirst insulating film 11, a second insulating film 12, a thirdinsulating film 13, a fourth insulating film 14, a fifth insulating film15, a sixth insulating film 16, the light-shielding layer LS2, thesemiconductor layer SC2, the gate line G2, the source line S2, the relayelectrode RE, the common electrode CE, the pixel electrodes PE1 and PE2,a first alignment film AL1, etc.

The first insulating substrate 10 is a light transmissive substrate suchas a glass substrate or a resin substrate. The first insulating film 11is formed on the first insulating substrate 10. The light-shieldinglayer SL2 is located on the first insulating film 11. The lightshielding layer LS2 serves as a shield against light transmitted from abacklight unit BL which will be described later to the semiconductorlayer SC2. The light-shielding layer LS2 is formed of a metal materialsuch as titanium (Ti), for example. The second insulating film 12 coversthe light-shielding layer LS2 and is also formed on the first insulatingfilm 11. The semiconductor layer SC2 is located on the second insulatingfilm 12 and partially overlaps the light-shielding layer LS2. Thesemiconductor layer SC2 is formed of a transparent amorphous oxidesemiconductor (TAOS), for example. The third insulating film 13 coversthe semiconductor layer SC2.

The gate electrode GE, which is part of the gate line G2, is located onthe third insulating film 13 and is covered with the fourth insulatingfilm 14. The gate electrode GE is located directly above a region of thesemiconductor layer SC2 which is opposed to the light-shielding layerLS2. The gate line G2 is formed of a metal material such as aluminum(Al), titanium (Ti), silver (Ag), molybdenum (Mo), tungsten (W), copper(Cu) or chromium (Cr), or alloy of these metal materials, and may have asingle layer structure or a multi-layer structure.

The source line S2 and the relay electrode RE are located on the fourthinsulating film 14 and is covered with the fifth insulating film 15. Thesource line S2 and the relay electrode RE are formed of the samematerial and may be formed of the above-described metal material. Thesource line S2 contacts the semiconductor layer SC2 in the contact holeCH2 which penetrates the third insulating film 13 and the fourthinsulating film 14. The relay electrode RE contacts the semiconductorlayer SC2 in the contact hole CH1 which penetrates the third insulatingfilm 13 and the fourth insulating film 14.

The common electrode CE is located on the fifth insulating film 15 andis covered with the sixth insulating film 16. The pixel electrodes PE1and PE2 are located on the sixth insulating film 16 and are covered withthe first alignment film AL1. The pixel electrodes PE1 and PE2 arepartially opposed to the common electrode CE via the sixth insulatingfilm 16. The common electrode CE and the pixel electrodes PE1 and PE2are formed of a transparent conductive material such as indium-tin-oxide(ITO) or indium-zinc-oxide (IZO). In a location overlapping an openingof the common electrode CE, the pixel electrode PE2 contacts the relayelectrode RE in the contact hole CH3 which penetrates the fifthinsulating film 15 and the sixth insulating film 16. In the exampleillustrated, the contact hole CH3 and the contact hole CH1 do notoverlap each other. The first insulating film 11, the second insulatingfilm 12, the third insulating film 13, the fourth insulating film 14 andthe sixth insulating film 16 are an inorganic insulating film of siliconoxide, silicon nitride, silicon oxynitride, etc., and may have a singlelayer structure or a multi-layer structure. The fifth insulating film 15is an organic insulating of acrylic resin, etc.

The second substrate SUB2 includes a second insulating substrate 20, thelight-shielding layer BM, a color filter CF, an overcoat layer OC, asecond alignment film AL2, etc.

The light-shielding layer BM and the color filter CF are located on aside of the second insulating substrate 20 which is opposed to the firstsubstrate SUB1. The light-shielding layer BM is formed of a blackcolored resin material, for example, and the pixels are partitioned bythe light-shielding layer BM. In the example illustrated, thelight-shielding layer BM is arranged in a region opposed to the sourceline S2, the gate line G2, the light-shielding layer LS2, the relayelectrode RE and the contact portion PB2. On the other hand, thelight-shielding layer BM is not provided in a region opposed to theelectrode portion PA1. The color filter CF is arranged in a locationopposed to the pixel electrodes PE1 and PE2 and partially overlaps thelight-shielding layer BM. The overcoat layer OC covers the color filterCF. The second alignment film AL2 covers the overcoat layer OC.

The color filter CF may be arranged in the first substrate SUB1. Thelight-shielding layer BM may be arranged between the color filter CF andthe overcoat layer OC or between the overcoat layer OC and the secondalignment film AL2. Further, a pixel which displays white may be added,and in this case, a white color filter may be arranged or an uncoloredresin material may be arranged in the white pixel, or the overcoat layerOC may be arranged without any color filter.

The first substrate SUB1 and the second substrate SUB2 are arranged suchthat the first alignment film AL1 and the second alignment film AL2 areopposed to each other. A predetermined cell gap is formed between thefirst alignment film AL1 and the second alignment film AL2. The cell gapis 2 to 5 μm, for example. The first substrate SUB1 and the secondsubstrate SUB2 are attached to each other by a sealant with thepredetermined cell gap formed.

The liquid crystal layer LC is located between the first substrate SUB1and the second substrate SUB2 and is held between the first alignmentfilm AL1 and the second alignment film AL2. The liquid crystal layer LCincludes liquid crystal molecules. The liquid crystal layer LC is formedof a liquid crystal material having positive dielectric anisotropy or aliquid crystal material having negative dielectric anisotropy.

With respect to the display panel PNL having the above-describedstructure, a first optical element OD1 including a first polarizer PL1is arranged below the first substrate SUB1. Further, a second opticalelement OD2 including a second polarizer PL2 is arranged above thesecond substrate SUB2. For example, the first polarizer PL1 and thesecond polarizer PL2 are arranged such that absorption axes thereoforthogonally cross each other in an X-Y plane. The first optical elementOD1 and the second optical element OD2 may include a retardation filmsuch as a quarter-wave plate or a half-wave plate, a scattering layer,an antireflective layer, etc., as needed.

In this structural example, the liquid crystal molecules included in theliquid crystal layer LC are initially aligned in a predetermineddirection between the first alignment film AL1 and the second alignmentfilm AL2 in an off state in which an electric field is not formedbetween the pixel electrode PE and the common electrode CE. In the offstate, the light emitted from the backlight unit BL toward the displaypanel PNL is absorbed by the first optical element OD1 and the secondoptical element OD2, and the display becomes dark. On the other hand, inan on state in which an electric field is formed between the pixelelectrode PE and the common electrode CE, the liquid crystal moleculesare aligned in a direction different from the initial alignmentdirection, and this alignment direction is controlled by the electricfield. In the on state, part of the light from the backlight unit BL istransmitted through the first optical element ODA1 and the secondoptical element OD2, and the display becomes bright.

FIG. 6 is a sectional view of part of the display panel PNL taken alongline C-D shown in FIG. 3.

The second portion PS22, the light-shielding layer LS2, the relayelectrode RE, the second portion PS32 and the light-shielding layer LS3are arranged in this order in the second direction Y between the firstinsulating substrate 10 and the common electrode CE. The gate lines G2and G3 are located directly above the light-shielding layers LS2 andLS3.

The pixel electrode PE1 and the pixel electrode PE2 are arranged in thesecond direction Y at a distance from each other on the sixth insulatingfilm 16. The electrode portion PA1 overlaps the second portion PS22. Thepixel electrode PE2 is located above the relay electrode RE and thesecond portion PS32. That is, the contact portion PB2 is locateddirectly above the relay electrode RE and contacts the relay electrodeRE in the contact hole CH3. The electrode portion PA2 extends from thecontact portion PB2 in the second direction Y and partially overlaps thesecond portion PS32.

On the other hand, in the second substrate SUB2, the opening OP1 and theopening OP2 are arranged in the second direction Y. The opening OP1 isopposed to the electrode portion PA1 and the second portion PS22. Thesecond opening OP2 is opposed to the electrode portion PA2 and thesecond portion PS32. A light-shielding layer BM1 located between theopening portion OP1 and the opening portion OP2 is opposed to thelight-shielding layer LS2, the gate line G2, the relay electrode RE andthe contact portion PB2. A light-shielding layer BM2 is located on theopposite side to the light-shielding layer BM1 with respect to theopening OP2, and is opposed to the light-shielding layer LS3 and thegate line G3.

According to the present embodiment, the second portion PS22 overlapsthe opening OP1. That is, the second portion PS22 is sufficientlyseparated from the gate line G2 and the light-shielding layer LS2.Therefore, parasitic capacitance formed between the semiconductor layerSC2, and the gate line G2 and the light-shielding layer LS2 can bereduced. Further, the semiconductor layer SC2 is formed of a transparentmaterial such as an oxide semiconductor. Therefore, even if thesemiconductor layer SC2 overlaps the opening OP1, it is possible toreduce parasitic capacitance between the semiconductor layer SC2, thegate line G2 and the light-shielding layer LS2 without reducing theaperture ratio of the display device.

On the other hand, if the semiconductor layer which constitutes theswitching element SW is formed of a semiconductor having low lighttransmittance such as polycrystalline silicon, for example, to preventreduction of the aperture ratio, the semiconductor layer needs to bearranged in a region in which the light-shielding layer BM is provided.In this case, the semiconductor layer cannot be sufficiently separatedfrom the gate line G2 and the light-shielding layer LS2, and as aresult, parasitic capacitance between the semiconductor layer, and thegate line G2 and the light-shielding layer LS2 cannot be reduced. On thecontrary, if the distance between the semiconductor layer, and the gateline G2 and the light-shielding layer LS2 is increased for the sake ofreducing the parasitic capacitance, the semiconductor layer is locatedin a region overlapping the opening OP1, and the aperture ratio may bereduced.

According to the present embodiment, it is possible to reduce theparasitic capacitance and maintain the aperture ratio by using thesemiconductor layer SC2 formed of a transparent material and separatingthe semiconductor layer SC2 away from the gate line G2 and thelight-shielding layer LS2 to the extent that part of the semiconductorlayer SC2 overlaps the opening OP1. Therefore, display qualitydegradation can be prevented.

Next, another structural example will be described.

A structural example shown in FIG. 7 differs from the structural exampleshown in FIG. 3 in that the relay electrode RE has a first region R1 anda second region R2. FIG. 7 shows the first substrate SUB1, but thelight-shielding layer BM provided in the second substrate SUB2 is shownby a dashed-dotted line.

The first region R1 and the second region R2 are located between thegate line G2 and the opening OP2. The first region R1 and the secondregion R2 are integrally or continuously formed with each other and areelectrically connected to each other.

The first region R1 has the shape of a rectangle, for example, andoverlaps the contact portion PB2. The first region R1 is located in asubstantially intermediate between the source line S1 and the sourceline S2 in the first direction X. The contact hole CH3 is provided in aregion in which the contact portion PB2 and the first region R1 overlapeach other. The contact portion PB2 contacts the first region R1 in thecontact hole CH3. A structure by which the contact portion PB2 and thefirst region R1 are connected is the same as the structure of thecontact hole CH3 shown in FIG. 3.

The second region R2 has the shape of a rectangle smaller than that ofthe first region R1, for example, and is farther from the gate line G2than the first region R1. In other words, the gate line G2, the firstregion R1 and the second region R2 are arranged in this order in thesecond direction Y. Further, the second region R2 is closer to thesource line S1 than the source line S2. That is, a distance (firstdistance) D22 between the source line S2 and the second region R2 isgreater than a distance (second distance) D12 between the source line S1and the second region R2. In the example illustrated, the second regionR2 overlaps an electrode portion (first electrode portion) PA21 locatedon the source line S1 side. The electrode portion PA21 is located in asubstantially center of the second region R2 in the first direction X.

The distance D22 is greater than a distance D21 between the source lineS2 and the first region R1 in the first direction X. On the other hand,the distance D12 is equal to a distance (third distance) D11 between thesource line S1 and the first region R1 in the first direction X. Inother words, a width (first width) WR2 of the second region R2 in thefirst direction X is less than a width (second width) WR1 of the firstregion R1 in the first direction X. In the example illustrated, thewidth WR2 is greater than the width of the electrode portion PA21 in thefirst direction X. For example, the distance D11 and the distance D21may be equal to each other.

The first end E1 overlaps the second region R2. The contact hole CH1 isprovided in a region in which the second region R2 and the electrodeportion PA21 overlap each other, and the contact hole CH1 is fartherfrom the gate line G2 than the contact hole CH3. In the exampleillustrated, the semiconductor layer SC2 is bent between the contacthole CH3 and the contact hole CH1. More specifically, the semiconductorlayer SC2 has a third portion PS23 and a fourth portion PS24 in additionto the first portion PS21 and the second portion PS22. The third portionPS23 extends from the first end E1 toward the gate line G2. The fourthportion PS24 extends from the third portion PS23 to between theelectrode portion PA21 and an electrode portion (second electrodeportion) PA22 located on the source line S2 side, and the fourth portionPS24 is connected to the first portion PS21.

FIG. 8 is a sectional view of the first substrate SUB1 taken along lineE-F shown in FIG. 7.

The source line S1 and the source line S2 are located on the fourthinsulating film 14 and are spaced apart from each other in the firstdirection X. The third portion PS23 is located on the second insulatingfilm 12 and is covered with the third insulating film 13. The thirdportion PS23 is located between the source line S1 and the source lineS2 in the first direction X, and is closer to the source line S1. Thesecond region R2 is formed on the fourth insulating film 14 directlyabove the third portion PS23. The second region R2 contacts the thirdportion PS23 in the contact hole CH1 which penetrates the fourthinsulating film 14 and the third insulating film 13 to the third portionPS23. The electrode portion PA21 and the electrode portion PA22 arelocated on the sixth insulating film 16 and are spaced apart from eachother in the first direction X. The electrode portion PA21 is locateddirectly above the third portion PS23 and the second region R2.

The same advantages as those of the structural example shown in FIG. 3can be obtained also in the present structural example. Further,according to the present structural example, the second region R2 isfarther from the source line S2 than the first region R1. Therefore,parasitic capacitance between the relay electrode RE and the source lineS2 can be reduced.

A structural example shown in FIG. 9 differs from the structural exampleshown in FIG. 7 in that the second region R2 is farther from the sourceline S1 than the first region R1.

The distance D12 is greater than the distance D11. In the exampleillustrated, the second region R2 is located in the intermediate betweenthe source line S1 and the source line S2 in the first direction X. Thatis, the distance D12 is equal to the distance D22. In the exampleillustrated, the second region R2 is located between the electrodeportion PA21 and the electrode portion PA22 and does not overlap theelectrode portion PA21 and the electrode portion PA22.

The same advantages as those of the structural example shown in FIG. 3can be obtained also in the present structural example. Further,according to the present embodiment, parasitic capacitance formedbetween the relay electrode RE and the source line S1 can be reduced.

As described above, according to the present embodiment, a displaydevice which can prevent image quality degradation can be provided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A display device comprising: a first substrateincluding: a first insulating substrate; a gate line located above thefirst insulating substrate and extending in a first direction; a firstlight-shielding layer extending in the first direction and overlappingthe gate line; a first source line and a second source line crossing thegate line and arranged in the first direction; a switching elementhaving an oxide semiconductor located between the first light-shieldinglayer and the gate line; and a first pixel electrode located between thefirst source line and the second source line; and a second substrateincluding: a second insulating substrate; and a second light-shieldinglayer located below the second insulating substrate and having a firstopening and a second opening, wherein the first opening and the secondopening are arranged in a second direction crossing the first directionbetween the first source line and the second source line, the gate lineand the first-light-shielding layer are between the first opening andthe second opening, the oxide semiconductor has a first portion and asecond portion, the first portion is connected to the first pixelelectrode and crosses the gate line and the first light-shielding layer,the second portion is connected to the second source line and overlapsthe first opening, and the first pixel electrode overlaps the secondopening.
 2. The display device of claim 1, further comprising a liquidcrystal layer between the first substrate and the second substrate. 3.The display device of claim 2, wherein the first substrate furtherincludes a second pixel electrode located between the first source lineand the second source line, and the second pixel electrode overlaps thefirst opening.
 4. The display device of claim 3, wherein a part of thesecond pixel electrode overlaps the second portion of the oxidesemiconductor.
 5. The display device of claim 1, wherein the firstlight-shielding layer has a first width in the second direction, thesecond light-shielding layer has a second width in the second directionbetween the first opening and the second opening, the gate line has athird width in the second direction, the second width is wider than thefirst width, and the first width is wider than the third width.
 6. Thedisplay device of claim 1, wherein the first light-shielding layer isconnected to the gate line, a first gate electrode of the gate lineoverlaps the first portion of the oxide semiconductor, and a second gateelectrode of the first light-shielding layer overlaps the first portionof the oxide semiconductor.
 7. The display device of claim 1, whereinthe first portion is connected to the second portion in an areaoverlapping the first opening, and the oxide semiconductor issubstantially L-shaped.
 8. The display device of claim 1, wherein thefirst portion is connected to the second portion, a first length of thefirst portion in an extension direction of the first portion is longerthan a second length of the second portion in an extension direction ofthe second portion, and the oxide semiconductor is substantiallyL-shaped.
 9. The display device of claim 1, wherein the first portion isconnected to the second portion, the first portion extends in adirection crossing the first direction, and the second portion extendsin a direction crossing the second direction.